Localization of nodes and device e.g. mobile devices in wireless communication networks, such as for instance Wi-Fi standards under 802.11x, Bluetooth, Zigbee standards under 802.15x, or any other suitable wireless communication network, has previously been based on so-called round trip time (RTT) measurements for receiving distance information between nodes. Different solutions have been utilized, such as time of flight, time of arrival, angle of arrival but all with limited success regarding both range and accuracy. The current systems for positioning in the wireless networks has relevant drawbacks. The precision is poor using RTT due to the involvement of an unknown processing time/time delay in a node after first receiving a message signal from a device before the signal is sent back to the node. The processing time is non-deterministic and varies between different devices in a wireless network. Furthermore, such processing times can vary within specific devices due to the work load of the processor.
One solution to the problem of determining an accurate distance between nodes in a wireless communication network would be to exclude the processing time by measuring only the Time of Flight between two nodes. However, this requires that the same time base is used at both nodes, which presents a similar problem as the one described for RTT. Achieving a mutual time base in different nodes requires synchronization between said nodes. Such synchronization is, in a similar way as when measuring RTT, affected by processing times in the nodes. Thereby, the original problem is recreated.
Furthermore, conventional systems such as Wi-Fi and Bluetooth have only a short distance of range which make the systems unpractical and difficult to extend into larger environments.
Yet another problem with prior art solutions is that RTT measurements only provides a distance as the result. The distance to an object can for many implementations be very useful but at the same time there are many application areas that would require a position instead of merely a distance. In order to solve this issue attempts to combine technologies has been presented in prior art, such as solutions wherein signal strength is used to determine a direction, so called angle of arrival. The accuracy of angle of arrival measurements is dependent of the frequency of the signal, echoes, and topography that all affects the performance. In prior art attempts to solve those issues are presented, for example a known solution in the art is to allow a user or device to rotate with a shield while measuring signal strength in order to together with a compass or gyro establish a direction. This works well but requires the user to perform an action or the device to have complex mechanics to perform the same operation automatically. Thereby are those solutions unpractical to implement in both mobile devices and other types of nodes, such as smartphones or access points.
As known in the art there are other solution commonly used for positioning, such as global positioning systems, especially GPS and GLONASS systems. GPS systems have good accuracy and works well outdoors but have numerous of issues relating to energy consumption, indoor coverage, and coverage in crowded cities with tall buildings surrounding the open streets.
In order to address the problems with GPS there are solutions available on the market utilizing triangulation wherein multiple nodes sends signals to a device and triangulates the position of the device. Those solutions have shown to generally have bad coverage and requires fixed networks with multiple nodes.
With the above solutions in mind it would be advantageous to provide a wireless communication positioning system and method that would allow for more accurate position determinations without the drawbacks of the prior art.